Ceramic structure and method for making same



F. P. LESTER Erm. 2,839,209

CERAMIC' STRUCTURE AND METHOD FOR MAKING SAME June 17, 1958 Original Filed Feb. 12, 1954 v amm June 17, 1958 F. P. LESTER Erm.

CERAMIC STRUCTURE AND METHOD FOR MAKING SAME Original Filed Feb. l2, 1954 2 Sheets-Sheet 2 Y INVENTORS EJ-ffl? 'fr 2,839,209 Patented June 17, 1958 CERAWHC STRUCTURE AND METHGD FR MAKENG SAME Frank P. Lester and Marianne Lester, Hartsdale, N. Y.

Continuation of application Serial No. 499,36', February 12, 1954. rthis application March l, 1955, Serial No. 491,261 Y s claims. (ci. 21e- 13) This invention relates to receptacles or containers for foods, drugs and other materials and more specifically concerns among other things an improved ceramic container particularly adapted for the storage of hot and cold food and other products to impede the discharge and absorption of heat and an improved method for manufacturing such containers. This application in one aspect constitutes a continuation of our application for U. S.

, patent Serial No. 409,868, led February l2,J 1954, now

abandoned, entitledY Ceramic Structure and Method for VMaking Same and in another aspect constitutes an iudependent invention.

Objects and advantages of the invention will be set forth in part hereinafterrand in part will be obvious herefrom or may be learned by practice With the invention, the same being realized and attained by means of the instrumentalities, combinations and methods pointed out in the appended claims: Y Y y Y The invention consists in the novel parts, arrangements, combinations, improvements and methods herein shown and described. Y v

The accompanying drawings referred to herein and constituting part hereof, illustrate certain embodiments of the invention and together with the description serve to explain the principles of the invention.

ln the drawings:

Fig. 1 is a perspective View of one embodiment of a ceramic vessel or container in accordance with the invention;

Fig. 2 is a cross sectional view of the embodiment of the invention shown in Fig. l;

Fig. 3 is a cross sectional view of another embodiment of the invention; v

Figs. 4A to 4F show several steps in accordance with one method of rhakinga ceramic structure in accordance with the invention;` and Figs. `5A through 5D illustrative anotherV method of fabricating a ceramic article in accordance with the inventio'n. p

Broadly the invention concerns a double walled ceramic structure constructed and sealed to provide a substantially air tight compartment between the walls. Notwithstanding the presence or absence of air in the compartment, it has been found that the structure can be subjecte'd-to temperature dilerence of 500 F. and even greater without the danger of cracking or otherwise dan aging the walls. In addition actual testsrhave shown that this invention, when used in the form of a bucket for the storage of hot or cold foods or other products, will substantially maintain the temperature of such products for extended periods ottime. While ceramic structures have heretofore been made with double walls, in order to conserve materials, to our knowledge they did not contemplate nor were they so arranged and constructed as to attain the objects and advantages of this inven- V tion.

ln another aspect, the invention is useful for the storage of products such as tobacco, cigarettes or other articles requiring a humid atmosphere.

rl`his new and improved structure which may be applied to ice buckets, soup tureens, tea and codec pots, trivits, hot plates, food warmers, transportation of drugs and other similar purposes, may be arranged as inentioned above with either a dead air space or vacuum between the walls. In the latter case the opening to the air space may be closed by a ceramic plug inserted before tre initial firing whereby a vacuum is produced during the tiring procedure as will be discussed in connection with the gures.

teferring now to the drawing, and( more specically to Fig. 1 thereof showing a ceramic structure 10 in accordance with the invention, this embodiment is in the Y form of a bowl that may be used for ice, hot foods and the like though it will become apparent that the principles thereof may be employed in other articles such as shallow dishes, glasses, cups, pots, trivits, etc. The bowl vitl is shown in cross section in Fig. 2 and may be provided with a cover 1l. of metal, ceramic or other suitable material. K

More specifically, the bowl 1G consisting of inner and outer members and 14 nested one within the other so that a substantial space i6 is formed between the inner and outer walls. The two members are joined one to the other about the edge of the bowl and this edge maybe recessed as shown at 20 to receive a suitable cover. While these mem-bersV may be joined in any desired manner, it is of course preferred that they be formedl integrally one with the other to form a unitary structure and the coinpleted'artiele is provided with a suitable glaze 23 on all exposed surfaces te water proof the ceramic body and o. of course provide a finished product.

` The space E116 bet-Ween the inner and outer bowl parts is preferably filled with a thermal insulating material such as mica particles or the like of a size that will pass through a 6 or 8 mesh though any suitable substance may be used. This material is inserted through the opening 2i either before or after the bowl is tired and the opening is closed by a plug 22 that is preferably of a waterproof material. if the plug is inserted before I'nring it is apparent that it must withstand the liring temperatures'and have a coeicient of'expansionV approximately equal to that of the ceramic material. Similarly the ller must also be able to withstand the :ring temperatures if inserted before tiring. While any suitableV cement may be used as a plug in the case where the plug is inserted after ring it is preferable to incorporate about 5% iron filings in the mixture in order to secure a more perfect bond between the plug and the body of the structure.

Since' the invention is intended for use as a thermal insulating device, the overlying layers of the composite w-ali structureV and the glaze must be able to withstand temperature differentials of the order of 530 Pfand even greater and of course withstand any pressures that may be created within the space dby reason of these temperature differences. A ceramic body mixture meeting these requirements may be made by mixing the following materials in their dry state:

Parts Powdered glass 12 Bedminster clay V9.5 Jordan clay 26 Victoria clay 7.5

To this mixture is added 32.5 liters of water for each 100 lbs., 153 cc. sodium silicate and 130 grams sodium 4' Hudson jint 103 S102 99.92 VF6203 .012 A1203 .04 T102 .008 CaO Trace MgO rTrace Bainbridge felaspar S102 65.5 A1203 20.3 Fegch;` l i Ignition loss 2,k Cao L 2.0 Mg@ Trace N320 Kao 5.2

' Jordan clay S102 70.02 A1203 F6203 j 1.57 T102 1.02 Ignition Y 6,19 C210 0.18 MgO 0.23 Na20 0.62 Kao l 1.94Y

Barkeil talcl#24 Si02 Y A1203 1.0` Fe2O3 0.2 Ti02 Trace to 0.05 Y Ignition 4.1 CaO 6.0-8.0 MgO In applying the `glaze tothe ceramic body it is prefer,- Y Y able to coat the body or structure with the glaze after Y drying and before ring whereupon only one iiring will Y cost of the linished article. Y

carbonate. Y e The-glaze is of course equally as important Vas the ceramic body and an excellent white glaze may be made 5 by preparing a dry mix of the following ingredients:

Y Parts Powdered glass 22 Bainbridge feldspar 11,95 Bedminster clay 5 Layton clay 5.95 Calcined zin` 5.60 White lead Y 10.4 Whiting 3,55 Tin mride 23.75 Zirconium scafe 23.75

' Borax 4.5

, When the basic mix is completed then add 2 parts of 20 talc for every 5 parts of the mixture andY then approximately 3'parts Ywater foreach part of the final mixture including the talc. Y Y

While the chemical composition of the several clays e' used in forming the ceramic body and the glaze in accordance with this invention varies from one batch to another the general accepted composition of theseclays are as follows:

` Bedminszer clay Y Si02 Y. Y 52.10 A1203 32.47 VI'1e2()3 TiOZ 1.31 Ignition' 9.13 n CaO 0.24 MgO 0.55 Na20 0.48 1x20 2.20 40 Layton clay Si02 47.96 A1203 36.62 4o F6203 i TiO2 Y 1.23 'Ignition 12.84 CaO 0.22 i MgO V0.74 :I0 N220 0.31V 'L KzO TraceV n Y Victoria Vclay S102 58.76 i A1203 27.01 Fe203 Y 0.8775 TiO2. Y 41.56 Ignition 10.55 C30 Y 0.29V 'Mgo Y 0.37 *NazO n 0.36 KBO 0.27

Exeter clay Y i S102 47.83 A1203 Y 38.92 F6203 0.30

None i() Ignition Y 1 11.70 C30.. None Mgg.. 0.77 N120..- 0.41

KBO. Y` 0.64 75 While the embodiment of the invention illustrated Y Figs. 1 and 2 is particularly useful as a thermal-insulating device for 'holding hot or cold materials, it can with a slightmodication shown in Fig. 3 be used for provid-Y Ving a humid atmosphere for articles such Yas tobacco and phere within the bowl. YSincertheVv outer membery 14'Y of Vthe bowl is glazed, vthe moisture retainedrby the yfiller and wall of the inner member `12 can escape onlythroughrthe wall 12. `YThus any material retained within the bowl will of course be maintained in a moist condition forfex-i tended periods of time without any danger of spilling the water or damagingthe material byrdirect contactV theree with.

As previously pointied'cfutthe*v embodiment of ligl` may be prepared either with or without fa yvacuum in;

theucompartment or space` 16. The production of a vacuum within the space 16 may be accomplished in a manner now to be described in :connection with Figs. 4A to 4F inclusive. f e Y Fig. 4Y illustrates a mold, in cross section, V'havingea' configuration Ythat may Vbe used in .casting orrmolding .a

structure of the type shown in Figs. 1 to 3 inc. The body 25 of the mold is preferably of plaster of Paris or other suitable water absorbent material and is formed with a cavity 26 corresponding to the shape of the ceramic structure to be made. An opening 27 is provided in the top for insertion of the liquid ceramic mix as described above. This mix is permitted to remain in the mold a sulcient time to allow desired thickness of ceramic to be deposited about the walls of the cavity 26. The mold is then inverted to remove the excess mix and leave the deposited material in place. Thus a hollow structure is formed with an opening 21 as shown in Fig. 2.

The body 25 of the mold is of course made in two parts which are separated for the removal of the molded structure. This structure is shown in Fig. 4B and the finished casting has the inner and outer members 12 and 14 as discussed in connection with Figs. l to 3. In the manufacture of ceramic articles, one of two procedures may be employed for setting or tiring the ceramic. One procedure involves a single tiring wherein both the body and glaze are tired at the same time while in a double ring procedure the body is tired and then the glaze is applied and the article is tired again. Should the double firing procedure be employed, the structure of Fig. 4B is tired before any further processing steps. Should a single tiring procedure be desired the structure of Fig. 4B is merely allowed to dry. Assuming for the present a single tiring procedure, the next step is to iill the cavity 16 with an insulating material such as mica or the like that will withstand the high tiring temperature usually of the order of 2200 F. The hole 21 is then iilled with a ceramic mix identical to that used for the body but of a somewhat more viscous consistency to form the plug 22 in Fig. 4D. As soon as the plug dries, a glaze 23 is applied to all outside surfaces as illustrated in Fig. 4E. The entire assembly is now fired and in so doing the ceramic body consisting of the members 12 and 14 assumes a permanent set. This occurs however at a lower temperature than that at which the glaze melts. As a result the expanding air within the cavity 16 will leave through the minute pores of the body and the plug 22 will become firmly and intimately bonded to the edge of the opening 2l to form a substantially unitary outer member i4. As the temperature of the furnace is raised to about 2200 F., the glaze melts to seal the pores in the ceramic body and provides the desired finish for the article. Now as the furnace is cooled the glaze sets and prevents air from reentering the cavity 16 thereby causing a vacuum to be produced r therein. Moreover the pressure of the air on the outside of the body tends to force the glaze into close contact with the body and eliect an improved bond therebetween.

If a double firing procedure is desired the structure of Fig. 4B is tired and then the steps of Figs. 4C to F are followed as described above. Should a vacuum not be desired within cavity 16, the body of the structure and glaze may be processed by either the single or double tiring procedures and then upon inserting a suitable filler, a plug 22 formed of any suitable cement may be used to close the opening 21. As pointed out above in cernents of this character it is preferable to incorporate iron filings in the cement to effect a more perfect seal.

Still another method of fabricating a container in accordance with the invention is illustrated in Figs. 5A through 5D. The container of Fig. 5A corresponds generally with that shown in Fig. 4C and has an inner v/all l2, an outer wall 14, a suitable insulating material 1e such as pulverized mica or the like disposed between the inner and outer walls and an opening 21 in the outer Wall 14. It will be observed that the container as illustrated in this figure is in an inverted or firing position. At this step in the process the container has not been fired but merely filled with the insulating material 16. The next step in the process constitutes the application of a glaze 30 to all outer surfaces of the container as illustrated in Fig. 5B including the edges of the opening 21. When the glaze 30 has dried a plug 3i having an air dried ceramic body 32 and an outer air dried glaze 33 identical to the glaze 30 isA placed lightly within the opening 21. This is shown in Fig. 5C of the drawings wherein it will be observed that the plug 31 by reason of a slightly tapered construction will be solely supported by the edges of the opening 21 with the top surface of the plug substantially below the raised edge 34 disposed about the periphery of the container base.

The container prepared in the manner illustrated in Fig. 5C is now tired by raising the temperature gradually to about 2200 F. As the furnace is heated the air remaining within the space between the walls 14 and 16 will expand and be discharged from the container primarily about the edges of the plug 31. At this point the ceramic container body has assumed a substantially permanent set and the glaze has melted. As the furnace is allowed to cool the glaze surrounding the plug 31 and the opening 2l will begin to set along with the glaze on the other parts of the container body. Inasmuch as the glaze forms a relatively dense impervious coating the hardening of the glazes about the plug 31 and in the opening 21 which have at this point melted and become intimately mixed one with the other forni an air tight seal. The simultaneously hardening of the glaze on the walls 12 and 14 prevents the intake of air through other portions of the ceramic body. Thus when the container is finally brought to room temperature a substantial vacuum will have been created between the walls 12 and 14 which materially adds to the insulating qualities of the article.

The inished article prepared in accordance with this procedure is illustrated in Fig. 5D and it will be observed that the glaze about the plug 31 has formed small llets 35 and 36 about the inner and outer edges of the plug which indicates the production of an eiiective seal between the plug and the container body. In this way a substantially unitary structure is formed having inner and outer walls with a vacuum created therebetween. By preparing the container in this manner the cost of construction is materially reduced and the plug cannot be dislodged from its opening by reason of physical or thermal shock and there is no danger of fluids seeping through the container walls and creating dangerously high steam pressures should the container be used for baking or cooking purposes.

It is apparent that the principles of the invention as described above may be readily applied to any type or shape of ceramic structure wherein heat insulating properties are required. Tn addition certain principles of the invention are also applicable to structures of the -type discussed in connection with Fig. 3 for humidifying purposes.

While only certain embodiments of the invention have been shown and described it is evident that other modirications, changes and alterations may be made without departing from the true scope and spirit thereof.

What is claimed is:

l. A ceramic structure having at least one wall comprising at least two spaced overlying layers of ceramic material consisting essentially of l2 parts powdered glass, 91/2 parts Bedminster clay, 26 parts Jordan clay, 7% parts Victoria clay, 4 parts Layton clay, l0 parts Exeter clay, 8 parts syanite, l0 parts aluminum silicate, 3 parts Barker talc, ll parts Hudson iiint No. 193, and 32% liters of water containing 153 cc. sodium silicate and i3() grams of sodium carbonate foreach l0() pounds of water,V

said layers being integrally formed one with the other, means sealing the space between said layers and a low density insulating material substantially filling said space.

7 -2.2A-ceramic structure aecording to claim 1 wherein 'saidv ller material is mica. 1 Y

, 35A ceramic: structure according to claim 1 wherein said"structure is coated With aeglaze consisting essentially -of 22 parts 'powdered glass, 11.9 Vparts Bainbridge feld- 5 vspar, 5 parts Bedminster clay, 5.9 parts Layton clay, 5,6 parts calcined zinc, 10.4 parts white lead, 3.55 parts whiting, 23.75 parts Vtin oxide, 23.75 parts zirconium silicate,

4.5 parts of boraX, 2 parts of Barker talc for every 5 parts nal mixture. 'Y

. UNITED V,Simms PATENTS 4smith -.-r oer. 17, 195o Y FOREIGN PATENTS Great Britain July 2,719725 Great Britain Feb. 25,"1915 Y 

1. A CERAMIC STRUCTURE HAVING AT LEAST ONE WALL COMPRISING AT LEAST TWO SPACED OVERLYING LAYERS OF CERAMIC MATERIAL CONSISTING ESSENTIALLY OF 12 PARTS POWDERED GLASS, 91/2 PARTS BEDMINSTER CLAY, 26 PARTS JORDAN CLAY, 71/2 PARTS VICTORIA CLAY, 4 PARTS LAYTON CLAY, 10 PARTS EXETER CLAY, 8 PARTS SYANITE, 10 PARTS ALUMINUM SILICATE, 3 PARTS BARKER TALC, 11 PARTS HUDSON FLINT NO. 103, AND 321/2 LITERS OF WATER CONTAINING 153 CC. SODIUM SILICATE AND 130 GRAMS OF SODIUM CARBONATE FOR EACH 100 POUNDS OF WATER, SAID LAYERS BEING INTEGRALLY FORMED ONE WITH THE OTHER, MEANS SEALING THE SPACE BETWEEN SAID LAYERS AND A LOW DENSITY INSULATING MATERIAL SUBSTANTIALLY FILLING SAID SPACE. 